When Nichola Curran missed her period three months in a row, she tried to brush it off as "just one of those hormonal things". After all, as a 19-year-old student, becoming a mother was the last thing on her mind – and she was taking the Pill to be sure.

Deep down though, the Dublin woman knew she had a difficult decision ahead.

"When I found out I was pregnant, I was like: 'Oh my God, what am I going to do?'" says Nichola, now a 31-year-old mother of two.

"I was so young and scared of what was going to happen. At 19, I was in no way planning on having a baby. I was in college and planning on going off to Australia for a year. My life was revolving around my social life – just kind of drinking and partying."

"I was on the Pill, but I was really reckless with it. So when I got pregnant, even though I was shocked, I wasn't really that surprised. I didn't even bother doing a home (pregnancy) test, I just went straight to the doctor."

Although "totally pro-choice", Nichola decided against an abortion.

"It did (cross my mind) for a couple of days," she admits. "But then I was like, 'Oh God, I can't do that.'

"The fact that you had to travel to get an abortion . . . it's still quite taboo. You just don't really do it. I didn't tell anybody for five months. Secretly, I think I knew that if I left it long enough there would be nothing I could do about it."

Nichola, who is a freelance make-up artist, explains: "Once the reality of the situation I'd gotten myself into kicked in, I stopped going out drinking, quit college and got a job.

"Looking back, it actually gave me the kick up the backside I needed. It gave me a purpose in life."

As Taoiseach Enda Kenny last week admitted a "duty" to legislate for limited abortion in Ireland, the story of Nichola's unplanned pregnancy is far from unique. More than 5,000 women picked up the phone to the Irish Family Planning Association (IFPA) last year after discovering that they were pregnant.

"At that counselling session, we talk through the three options with the woman, which are parenting, adoption and abortion. It's up to the woman to then decide which one she wants to go for."

Although the number of Irish women travelling to the UK for an abortion has gone down from 6,673 in 2001 to 4,149 in 2011, one-third of pregnant women still say they weren't planning to have a baby in the first place, according to the most recent Irish Contraception and Crisis Pregnancy study.

"About a third of women who have been pregnant have reported experiencing a crisis pregnancy," says Orla McGowan, education and information officer of the Crisis Pregnancy Programme. "That (figure) is relatively stable over the last seven years.

"We know that crisis pregnancy is more likely to happen to younger women – 44pc of women aged 18-25 have said that their pregnancy is a crisis, compared to 11pc of those aged 36-45. The majority – 62pc – go on to have the baby."

With everyone from John Bruton to Richard Branson rowing in on the abortion debate however, one question remains unanswered. Almost three decades after condoms went on sale over the counter here, why are so many couples still getting caught out?

"Sometimes the contraception that the woman is using has failed," says Niall Behan of the IFPA. "Most of the time it's a failure to use contraception."

"About 25pc of women who experienced a crisis pregnancy didn't use contraception because they didn't think they were at risk of becoming pregnant at the time of conception," adds Orla McGowan. "They just thought: 'It won't happen to me.'

"The main reasons women give for the pregnancy being a crisis is that it wasn't planned or that they're too young to have the baby. Being unmarried, relationship difficulty and fear of family reaction are some of the others."

Not all crisis pregnancies are unplanned, however, and not all unplanned pregnancies are necessarily a crisis.

"There's a big debate around whether you should use 'crisis pregnancy' or 'unplanned pregnancy'," explains Niall.

"We tend to use 'unplanned pregnancy' because sometimes a planned pregnancy can turn into a crisis, for example, where there's a diagnosis of a fatal foetal abnormality."

"An unplanned pregnancy may not be a 'crisis pregnancy,'" agrees Orla. "You may not have planned a baby, but when you discover you're pregnant, you may be delighted.

"Basically, a 'crisis pregnancy' is defined as a pregnancy that a woman experiences as a crisis for various reasons."

For those hoping to avoid pregnancy of any description, there are plenty of options says Dr Gillian Darling of Leopardstown Women's Medical Clinic.

"All contraception is available in Ireland," she says. "There's the Pill, the mini-Pill, or, for people who can't remember to take the Pill, the patch or the ring, which contain the same ingredients absorbed through the skin and vagina (respectively).

"Long-acting reversible contraceptive, what they call LARCs, are the Mirena coil, which stays in (the womb) for five years; the copper coil, which stays in for three to 10 years, depending on the type and (contraceptive implant) Implanon, a bar that goes under the skin for three years.

"Depo-Provera, an injection of a hormone once every 12 weeks, is reversible, but it can take a while to come out of your system after you stop.

"For barrier methods, there's also the diaphragm and condom. The female condom never really took off in Ireland. It's not that safe, quite expensive and apparently very noisy as well."

Dr Darling adds: "The Mirena would probably be one of the most effective. Depo, Implanon and the Pill are all very high safety as well. But nothing is 100pc.

"With unplanned pregnancies, it's usually either no contraception, split condoms, missed Pills or Pills after vomiting or diarrhoea. There are also a lot of women in their 40s who feel that they wouldn't get pregnant and they do.

"If your periods stop before you're 50, wait two years before you're safe [to have unprotected sex without risking pregnancy]. If they stop after you're 50, wait one year. Otherwise, you can still get pregnant."

Despite the widespread availability of contraception here, 30pc of women admit to regularly playing "Catholic roulette" with their birth control, according to a survey by condom company Durex.

"Attitudes to contraception have changed very significantly over the years," says Niall Behan of the IFPA. "No one is campaigning against contraception the way they were at one stage. But there are still barriers."

It costs around €350 for a coil, €4-€13 a month for the Pill and €4 for a three-pack of condoms. "Cost is definitely an issue," adds Behan. "The cost of contraception is still very, very high in Ireland – particularly the most effective long-acting contraception."

More than 70pc of Irish women admit to having had unprotected sex, with a third saying it was because they didn't have any protection at the time, according to Durex.

So how does Think Contraception's latest TV ad, 'Johnny's Got it Covered', which shows a young woman whipping out a condom at the last moment, compare to the reality?

"Contraception use is actually quite high among young people," says Orla McGowan of the CPP. "Eighty per cent of young people use contraception consistently. But obviously that means there are still 20pc who don't – and that is a concern.

"It's important to get the message across that both the man and woman are responsible for contraception. We wanted to show that it's normal for a girl to have a condom with her."

Ten years and two sons on, Nichola joked that she's definitely taken control of her fertility.

"With my second son Cole (4), it was very much planned," she explains.

"I had the [Mirena] coil in, but got it taken out after three years. After I got it taken out, I got pregnant very quickly. I do have friends who don't believe in contraception, they just take their chances – but I'm not taking any more chances. As soon as I could, (the coil) went straight back in. It's in there now – and it's staying in there!"